The present invention generally relates to constant velocity joints, and more particularly, relates to a shield for use within a constant velocity joint.
Constant velocity joints (CV joints) are common components in automotive vehicles. Typically, constant velocity joints are used where transmission of a constant velocity rotary motion is desired or acquired. The common types of constant velocity joints are a plunging tripod, a fixed tripod, a plunging ball joint and a fixed ball joint. These types of joints currently are used in front wheel drive vehicles, rear wheel drive vehicles and on the propeller shafts found in rear wheel drive, all wheel drive and four wheel drive vehicles. The constant velocity joints are generally grease lubricated for life and sealed by a sealing boot when used on drive shafts. Therefore, constant velocity joints are sealed in order to retain grease inside the joint while keeping contaminates and foreign matter, such as dirt and water, out of the joint. To achieve this protection the constant velocity joint is usually enclosed at the open end of the outer case by a sealing boot made of a rubber, thermoplastic or silicone. The opposite end of the outer race generally is enclosed by a dome or cap, known as a grease cap in the case of a disk type of joint. A monoblock or integral stem and race design style joint is sealed by the internal geometry of the outer race. This sealing and protection of the constant velocity joint is necessary because contamination of the inner chamber of the outer joint generally will cause internal damage and destruction of the joint. Furthermore, once the inner chamber of the outer joint is partially filled and thus lubricated, it is lubricated for life.
A constant velocity joint""s main function is the transmission of rotational movement. During operation, the constant velocity joint transmits torque. The torque transfer generates heat by the internal frictions of the joint along with other transmission inefficiencies. Generally, as the speed and torque increase, the heat generation of the constant velocity joint also increases. A further effect of increased speeds is that the velocity of the grease increases because the internal action of the ball in the tracks acts like a pump which cause the grease to be pumped out of the tracks and into the boot. This causes increased pressure on the boot. High internal temperatures in the constant velocity joint effect the lubricant grease, which is in contact with the boot. With higher temperatures the boot becomes vulnerable to cracking and rupture which will reduce the life of the constant velocity joint, which is supposed to be sealed for life. Furthermore, if any heat that is created is transferred to the outer race, it is thereafter transferred to the boot which will further reduce the life of the boot material and create premature cracks, ruptures and blow outs of the boot thus compromising the constant velocity joint. The grease/heat shield prevents this pumping action of the grease into the boot.
Therefore, there is a need in the art for a constant velocity joint that is able to protect the boot and sealing system from the heat and grease found within the constant velocity joint. The heat and lubricant must be kept from contacting and deteriorating the boot which will result in eventual failure of the sealing system of the constant velocity joint.
One object of the present invention is to provide an improved constant velocity joint.
Another object of the present invention is to provide a barrier between the boot and sealing system of a constant velocity joint and the heat and lubricant found within the constant velocity joint.
Yet a further object of the present invention is to provide a two piece barrier for a constant velocity joint.
Still a further object of the present invention is to provide a shield that will also act as a gasket allowing it to create an o-ring type seal.
Yet a further object of the present invention is to provide a shield made of a material that has insulating characteristics that will reduce any heat transfer.
To achieve the foregoing objects a barrier for use in constant velocity joint is disclosed. The constant velocity joint has a lubricant within an outer race and a boot secured to a boot cover. The barrier includes a shield that is in contact with the outer race and the boot cover. The shield will have a body with a generally cup shaped cross section and have a circumferential flange extending from one end thereof.
One advantage of the present invention is that the constant velocity joint will have a shield that will keep grease and/or lubricant away from the boot therefore increasing the life of the boot.
A further advantage of the present invention is that the shield will create an insulating air gap further protecting the boot from heat and grease.
Still a further advantage of the present invention is that the shield will be made of material that will have insulating characteristics and will reduce the heat transfer from the outer race to the boot cover.
A further advantage of the present invention is that the shield will also act as a gasket like o-ring to create a seal between the boot cover and the outer race of the constant velocity joint.
A further advantage of the present invention is that the shield prevents a pumping action of the lubricant into the boot.
Other objects, features and advantages of the present invention will become apparent from the subsequent description and appended claims taken in conjunction with the accompanying drawings.